1. Field
One or more embodiments of the present invention relate to a battery pack.
2. Description of the Related Art
Typically, rechargeable batteries, unlike primary batteries that are not chargeable, are batteries that are charged and discharged. Rechargeable batteries are used as power sources for mobile devices, electric vehicles, hybrid vehicles, electric bicycles, and uninterruptible power supplies, etc. Batteries are used in the form of a single battery cell, or in the form of a battery pack formed by connecting a plurality of battery cells into one unit.
Small mobile devices, such as cellular phones, are operative with the output and capacity of a single battery for a predetermined period of time. However, when long-term driving and high-power driving are required, for example, when electric vehicles and hybrid vehicles which require high power consumption are used, a battery pack is more often used due to its increased output and capacity, and an output voltage or output current of a battery pack may increase according to the number of battery cells in the pack.
A battery pack requires an assembly structure for connecting a plurality of battery cells into one single assembly, and such an assembly structure provides a connecting force for integrating a plurality of battery cells. For example, a lithium ion battery may be used as a battery cell. However, although the performance of the lithium ion battery may not decrease even when charging and discharging are repeatedly performed, during charging, an anode may expand while lithium ions move. In particular, in the case of a battery pack formed by connecting the plurality of battery cells, even when each of the battery cells expands slightly, the battery pack including the battery cells may expand by 5 to 10%. As described above, when the battery pack is significantly deformed, electric resistance of battery cells increases and electric characteristics thereof may decrease.
Further, when a distortion moment is applied to a battery pack due to an external element, a distortion deformation may occur due to the lack of rigidity, and in this case, charging and discharging characteristics due to the deformation of the battery pack may deteriorate.